There are many books on Perl and Perl-related.
A few of these are good,
some are OK,
but many aren't worth your money.
There is a list of these books,
some with extensive reviews,
at http://books.perl.org/ .
We list some of the books here,
and while listing a book implies our endorsement,
don't think that not including a book means anything.

Each version of Perl comes with the documentation that was current at the time of release. This poses a problem for content such as book lists. There are probably very nice books published after this list was included in your Perl release, and you can check the latest released version at http://perldoc.perl.org/perlbook.html .

Some of the books we've listed appear almost ancient in internet scale, but we've included those books because they still describe the current way of doing things. Not everything in Perl changes every day. Many of the beginner-level books, too, go over basic features and techniques that are still valid today. In general though, we try to limit this list to books published in the past five years.